Production of cellulose ester textile materials



1951 P. F. c. SOWTER ET AL 2,552,598

PRODUCTION OF CELLULOSE ESTER TEXTILE MATERIALS Filed Aug. 9, 1949 Patented May 15, 1951 PRODUCTION OF CELLULOSE ESTER TEXTILE MATERIALS Percy Frederick Combe Sowter and Frank Brentnall Hill, Spondon, near Derby, England, assignors to Celanese Corporation of America, a

corporation of Delaware Application August 9, 1949, Serial No. 109,274 In Great Britain September 23, 1948 14 Claims.

This invention relates to the manufacture of cellulose ester yarns suitable for conversion into staple fibre.

In one method of making staple fibre from cellulose esters, in particular cellulose acetate, a tow or untwisted bundle of filaments is made and cut up; the tow is made up from untwisted yarns of high denier, e. g. about EGO-5,000 or more, which in turn are preferably made up from filaments of denier about 1.5-3.0; the yarns should be moderately strong and of good extensibility; for example they preferably have a tenacity of about 2.0-2.5 grammes per denier or more and a minimum extensibility of about A process to be suitable for making cellulose acetate material for conversion into staple fibre by this method should therefore be capable of producing yarns of high denier having the properties outlined above; furthermore it should be capable of operation at fairly high spinning speeds, and should make use of solvents and other agents that are easily made and recovered. The present invention provides a mean of satisfying these requirements.

According to the invention, yarns having a basis of a lower aliphatic ester of cellulose'and suitable for conversion into staple fibre are made by a process which comprises forming filaments from the cellulose ester by extruding an acetone solution of the cellulose ester into an aqueous solution of diethylene glycol diacetate of concentration below 38% as coagulating bath, stretching the filaments during their passage through the coagulating bath, and then subjecting the filaments to the action of a regulating bath compris- 1 ing an aqueous solution of diethylene glycol diacetate of concentration below 38% while allowing them to shrink freely. The filaments may then be washed substantially free from the diethylene glycol diacetate, for instance by means of cold or warm water, and dried. The invention is of particular importance for the maniacture of yarns from cellulose acetate, and it will be described with particular reference to this material.

It is very advantageous to subject the filaments in the form of untwisted yarn to the action of the regulating bath while passing over advancing rollers or a single advancing reel so shaped or adjusted as to allow the yarn to shrink fr y.

Generally it is sufiicient to allow for a shrinkage of about 2%4%, and this may be done by using a pair of slightly tapered rollers, one of which is fixed skew to the other so that the yarn travels across the rollers in the direction of the taper. Preferably one of the rollers dips into the regulating bath, but other methods of applying the bath to the yarn may be employed. For example the regulating bath may be sprayed onto or other wise applied to the yarn during its passage through the atmosphere over or between the rollers, or it may be applied by means of hollow perforated rollers. (It will be understood that, while, for convenience, the term regulating bath is employed to denote the diethylene glycol. diacetate solution with which the yarn is treated as described above, the word bath is not intended to imply the use of any particular method of applying the solution to the yarn.)

It is preferred to employ as the regulating bath a diethylene glycol diacetate solution of the same concentration as that used in the coagulating bath, but at a lower temperature. Advantageously the coagulating bath may comprise a diethylene glycol diacetate solution of concentration about 30%35% kept at a temperature between about 30 and 35 C. The temperature of the regulating bath is preferably about 815 Q. lower, i. e. between about 15 and 27 C. according to the temperature of the coagulating bath. If desired however the temperature of the regulating bath may be approximately the same as that of thewcoagulating bath and/or its concentration may be lower.

The spinning jet and coagulating bath may be arranged for either horizontal or vertical, preferably upward, spinning. The best length of the coagulating bath and length of travel of the yarn in contact with the regulating bath depend on a number of factors, including filament denier, the number of filaments in the yarn, the rate of travel of the yarn and the rate at which. spent liquor in the coagulating and regulating bath is replaced by fresh. It is in any case very desirable that the yarn should be substantially free from acetone before it leaves the regulating bath. As a general rule it may be said that the path of the yarn through the coagulating bath may be between about and cm. and the path of the.

moving the yarn from the water, or by causing Water to flow continuously over the yarn for some time, e. g. about 1-4 hours; advantageously a continuous wash of this kind may be followed by a wash in which the yarn is allowed to stand in water for several hours. The diethylene glycol diacetate can be recovered from the Wash water,

for example by extraction with benzene, and used again in a coagulating or regulating bath. If

desired, the wash water may be partly or wholly replaced by an organic solvent for diethylene glycol diacetate which is without action on cellulose acetate, e. g. petroleum ether.

A suitable form of device for carrying out the invention is illustrated diagrammatically in the drawing. 7

The device comprises a spinning jet i contain ing, for example, ZOO-1,000 holes of diameter 0.0'8- -0.12 mm., fed by a pipe 2 from a spinning pump and filters (not shown) and situated below the liquid level in a horizontal trough 3 provided with a liquid inlet 4 and overflow 5. The trough is kept filled to the overflow level with a 30%35% aqueous diethyleneglycol diacetate solution at a temperature kept between 31 and 33 C., which enters continuously through the inlet 1 and runs off by the overflow 5. Towards the further end of the trou h and about at the level of the surface of the liquid is a guide rod 6 adapted to lead the filaments formed in the coagulating bath as a single untwisted yarn to a godet I.

In line with the trough 3 is situated a second horizontal trough B provided with a liquid inlet 9 and overflow Ill for the regulating bath, and positioned above it a pair of tapered advancing rollers l I and I2, one of which dips below the surface of the liquid in the trough 8. The regulating bath is a solution of diethylene glycol diacetate of l the same concentration as that of the coagulating bath but kept at a temperature between 21 and 23 C. The rollers H and l2 both have a 1% taper along their length and one of them is mounted in adjustable bearings so that its axis can be adjusted to make any desired angle with the axis of the other and so cause the yarn to travel down the rollers in the direction of the taper. A second godet I3 is situated so as to receive the yarn leaving the advancing rollers. The godet l is preferably driven at such a speed as to impart to the filaments in the coagulating bath as high a degree of stretch as they will take without breaking, and godet l3 at a suitably lower speed to allow the yarn passing between the two godets and round the advancing rollers to shrink freely, e. g. at a peripheral speed 4% less than that of the godet 1.

In a modification of the invention, the regulating bath may comprise water alone instead of aqueous diethylene glycol diacetate, and in this case also the temperature is preferably, though not necessarily, below that of the coagulating bath. When using water the yarn does not as a rule shrink to any substantial de ree. and it is therefore advisable to employ cylindrical rather than tapered advancing rollers so as to avoid sagging without subjecting the yarn to any substantial degree of tension. However, since the regulating bath of aqueous diethylene glycol diacetate gives a product of greater tenacity and extensibility, its use is preferred.

Cellulose acetate yarns produced in accordance with the invention not only possess good tenacity and extensibility but also frequently have a considerable degree of crimp, making them very suitable for conversion into staple fibre.

Although the regulating bath is preferably of the same composition and may also be at the same temperature as the coagulating bath, its action differs from that of the coagulating bath, and the effect of employing a separate regulating bath is quite different from the effect of correspondingly increasing the time of travel of the yarn through the coagulating bath.

While the invention has been described with particular reference to cellulose acetate, it is also applicable to the production of yarn from other lower aliphatic acid esters of cellulose, especially cellulose propionate and acetate propionate.

Having described our invention, what we desire to secure by Letters Patent is: I.

l. The process for the manufacture of yarns having a basis of a lower aliphatic ester of cellulose and suitable for conversion into staple fibre, which comprises forming filaments from the cellulose ester by extruding through a multi-hole spinning jet an acetone solution of the cellulose ester into an aqueous solution of diethylene glycol diacetate of concentration below 38% as coagulating bath, stretching the filaments during their passage through the coagulating bath, and then subjecting the filaments, until they are substantially free from acetone, to the action of a regulating bath comprising an aqueous solution of diethylene glycol diacetate of concentration below 38% while allowing them to shrink freely.

2. Process for the manufacture of yarns having a basis of cellulose acetate and suitable for conversion into staple fibre, which comprises forming filaments from the cellulose acetate by extruding through a multi-hole spinning jet an acetone solution of the cellulose acetate into an aqueous solution of diethylene glycol diacetate of concentration below 38% as coagulating bath, stretching the filaments during their passage through the coagulating bath, and then subjecting the filaments, until they are substantially free from acetone, to the action of a regulating bath comprising an aqueous solution of diethylene glycol diacetate of concentration below 38% while allowing them to shrink freely.

3. Process for the manufacture of yarns having a basis of a lower aliphatic ester of cellulose and suitable for conversion into staple fibre, which comprises forming filaments from the cellulose ester by extruding through a multi-hole spinning jet an acetone solution of the cellulose ester into an aqueous solution of diethylene glycol diacetate of concentration 30% to 35% as coagulating bath, stretching the filaments during their passage through the coagulating bath, and then subjecting the filaments, until they are substantially free from acetone, to the action of a regulating bath comprising an aqueous solution of .di-

ethylene glycol diacetate of concentration 30% to- .35% while allowing them to shrink freely.

4. Process for the manufacture of yarns have.

ing a bas s of c llul e a e te and ui able f r conversion into staple fibre, which comprises forming filaments from the cellulose acetate by extruding through a multi-hole spinning jet an acetone solution of the cellulose acetate into an aqueous solution of diethylene glycol diacetate of concentration 30% to 35% as coagulating bath, stretching the filaments during their passage through the coagulating bath, and then subjecting the filaments, until they are substantially free from acetone, to the action of a regulating bath comprising an aqueous solution of di ethylene glycol diacetate of concentration 30% to 35% while allowing them to shrink freely.

5. Process for the manufacture of yarns having a basis of a lower aliphatic ester of cellulose and suitable for conversion into staple fibre, which comprises forming filaments from the cellulose ester by extruding through a multihole spinning jet an acetone solution of the cellulose ester into an aqueous solution of diethylene glycol diacetate of concentration 30% to 35% and at a temperature of 30 to 35 C. as coagulating bath, stretching the filaments during their passage through the coagulating bath, and then subjecting the filaments, until they are substantially free from acetone, to the action of a regulating bath consisting of an aqueous solution of diethylene glycol diacetate of the same concentration as the coagulating bath, and at a temperature 8 to 15 C. lower, while allowing them to shrink freely.

6. Process for the manufacture of yarns having a basis of cellulose acetate and suitable for conversion into staple fibre, which comprises forming filaments from the cellulose acetate by extruding through a multi-hole spinning jet an acetone solution of the cellulose acetate into an aqueous solution of diethylene glycol diacetate of concentration 30% to 35% and at a temperature of 30 to 35 C. as coagulating bath, stretching the filaments during their passage through the coagulating bath, and then subjecting the filaments, until they are substantially free from acetone, to the action of a regulating bath consisting of an aqueous solution of diethylene glycol diacetate of the game concentration as the coagulating bath, and at a temperature 8 to 15 C. lower, while allowing them to shrink freely.

7. Process for the manufacture of yarns having a basis of a lower aliphatic ester of cellulose and suitable for conversion into staple fibre, which comprises forming filaments from the cellulose ester by extruding through a multi-hole spinning jet an acetone solution of the cellulose ester into an aqueous solution of diethylene glycol diacetate of concentration below 38% as coagulating bath, collecting the filaments into an untwisted yarn and applying to the yarn a tension such that the filaments are stretched during their passage through the coagulating bath, and then subjecting the yarn, until it is substantially free from acetone, to the action of a regulating bath consisting of an aqueous solution of diethylene glycol diacetate of concentration below 38%, while allowing it to shrink freely.

8. Process for the manufacture of yarns having a basis of cellulose acetate and suitable for conversion into staple fibre, which comprises forming filaments from the cellulose acetate by extruding through a multi-hole spinning jet an acetone solution of the cellulose acetate into an aqueous solution of diethylene glycol diacetate of concentration 30% to 35% as coagulating bath, collecting the filaments into an untwisted yarn ing a basis of cellulose acetate and suitable for conversion into staple fibre, which comprises forming filaments from the cellulose acetate by extruding through a multi-hole spinning jet an acetone solution of the cellulose acetate into an aqueous solution of diethylene glycol diacetate of concentration 30% to 35% as coagulating bath, collecting the filaments into an untwisted yarn and applying to the yarn a tension such that the filaments are stretched during their passage through the coagulating bath, and then subjecting the yarn, until it is substantially free from acetone, to the action of a regulating bath consisting of an aqueous solution of diethylene glycol diacetate of concentration 30% to 35%, while allowing it to shrink freely, the number and dimensions of the holes in the spinning jet and the degree of stretch being so chosen that the yarn, after it has shrunk, has a denier above 500 while the individual filaments have a denier below 3.

10. Process for the manufacture of yarns having a basis of cellulose acetate and suitable for conversion into staple fibre, which comprises forming filaments from the cellulose acetate by extruding through a multi-hole spinning jet an acetone solution of the cellulose acetate into an aqueous solution of diethylene glycol diacetate of concentration 30% to 35% at a temperature of 30 to C. as coagulating bath, collecting the filaments into an untwisted yarn and applying to the yarn a tension such that the filament during their passage through the coagulating bath are stretched to substantially the highest degree possible without breaking them, and the-n subjecting the yarn, until it issubstantially free from acetone, to the action of a regulating bath consisting of an aqueous solution of diethylene glycol diacetate of the same concentration as the coagulating bath and at a temperature 8 to 5 C. lower while allowing it to shrink freely.

11. Process for the manufacture of yarns having a basis of cellulose acetate and suitable for conversion into staple fibre, which comprises forming filaments from the cellulose acetate by extruding through a multi-hole spinning jet an acetone solution of the cellulose acetate into an aqueous solution of diethylene glycol diacetate of concentration 30% to 35% at a temperature of 30 to 35 C. as coagulating bath, collecting the filaments into an untwisted yarn and applying to the yarn a tension such that the filaments during their passage through the coagulating bath are stretched to substantially the highest degree possible without breaking them, and then subjecting the yarn, until it is substantially free from acetone, to the action of a regulating bath consisting of an aqueous solution of diethylene glycol diacetate of the same concentration as the coagulating bath and at a temperature 8 to 15 C. lower while allowing it to shrink freely, the number and dimensions of the holes in the spinning jet being so chosen that the yarn, after it has shrunk, has a denier above 500 while the individual filaments have a denier below 3.

12. Process according to claim 1, wherein the 8- yarn is subjected'to the action of the regulating REFERENCES CITED ggg g on threadadvancmg thread'stor' I The, foilowing references are of record in the r e of th' t 13. Process according to claim 8, wherein the m 18 em yarn is'subjected to the action of the regulating 5 UNITED STATES PATENTS bath while on a thread-advancing thread-storage Number Name Date device. 0 2,070,630 Sowter Feb. 16, 1937 14. Process according to claim 11, wherein the 2,075,027 Dreyfus Mar. 30, 1937 yarn is subjected to the action of the regulating bath while on a thread-advancing thread-storage 10 device. ,7

' PERCY FREDERICK COMBE SOWTER.

FRANK BRENTNALL HILL. 

1. THE PROCESS FOR THE MANUFACTURE OF YARNS HAVING A BASIS OF A LOWER ALIPHATIC ESTER OF CELLULOSE AND SUITABLE FOR CONVERSION INTO STAPLE FIBRE, WHICH COMPRISES FORMING FILAMENTS FROM THE CELLULOSE ESTER BY EXTRUDING THROUGH A MULTI-HOLE SPINNING JET AN ACETONE SOLUTION OF THE CELLULOSE ESTER INTO AN AQUEOUS SOLUTION OF DIETHYLENE GLYCOL DIACETATE OF CONCENTRATION BELOW 38% AS COAGULATING BATH, STRETCHING THE FILAMENTS DURING THEIR PASSAGE THROUGH THE COAGULATING BATH, AND THEN SUBJECTING THE FILAMENTS, UNTIL THEY ARE SUB- 